This listing is for a Matched Set of 4 Harmony-Silvertone Volume-Tone Cupcake knobs. These knobs are from the 1960's and would have been found on a Harmony H-54 Rocket or similar guitar made by Harmony-Silvertone and Airline. 
The knobs are in very good functional. The show wear consistent with their age and the cream color has yellowed over time.
Please check out the pictures and message with questions.

Thanks for looking,,